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<p style="margin-top:0;margin-bottom:0">Acked-by: Alex Deucher <alexander.deucher@amd.com><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> amd-gfx <amd-gfx-bounces@lists.freedesktop.org> on behalf of David Francis <David.Francis@amd.com><br>
<b>Sent:</b> Tuesday, November 6, 2018 11:14:46 AM<br>
<b>To:</b> amd-gfx@lists.freedesktop.org<br>
<b>Cc:</b> Francis, David; Samantham@posteo.net; Wentland, Harry; Guttula, Suresh<br>
<b>Subject:</b> [PATCH] drm/amd: Don't fail on backlight = 0</font>
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<div class="PlainText">Amgpu's backlight update status function was<br>
returning 1 (an error value) when the backlight<br>
property was 0. This breaks users that assume<br>
0 is a valid backlight value (which is a<br>
correct assumption)<br>
<br>
If the user passes in a backlight value of 0,<br>
tell them everything is fine, then write a value of<br>
1 to hardware.<br>
<br>
Signed-off-by: David Francis <David.Francis@amd.com><br>
Bugzilla: <a href="https://bugs.freedesktop.org/108668">https://bugs.freedesktop.org/108668</a><br>
Fixes: 416615ea9578 ("drm/amd/display: set backlight level limit to 1")<br>
Cc: Suresh.Guttula@amd.com<br>
Cc: Harry.Wentland@amd.com<br>
Cc: Samantham@posteo.net<br>
---<br>
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 18 ++++++++++--------<br>
1 file changed, 10 insertions(+), 8 deletions(-)<br>
<br>
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c<br>
index f8ec8a146663..131e6483d442 100644<br>
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c<br>
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c<br>
@@ -1567,21 +1567,23 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)<br>
{<br>
struct amdgpu_display_manager *dm = bl_get_data(bd);<br>
<br>
+ /* backlight_pwm_u16_16 parameter is in unsigned 32 bit, 16 bit integer<br>
+ * and 16 bit fractional, where 1.0 is max backlight value.<br>
+ * bd->props.brightness is 8 bit format and needs to be converted by<br>
+ * scaling via copy lower byte to upper byte of 16 bit value.<br>
+ */<br>
+ uint32_t brightness = bd->props.brightness * 0x101;<br>
+<br>
/*<br>
* PWM interperts 0 as 100% rather than 0% because of HW<br>
- * limitation for level 0.So limiting minimum brightness level<br>
+ * limitation for level 0. So limiting minimum brightness level<br>
* to 1.<br>
*/<br>
if (bd->props.brightness < 1)<br>
- return 1;<br>
+ brightness = 0x101;<br>
<br>
- /* backlight_pwm_u16_16 parameter is in unsigned 32 bit, 16 bit integer<br>
- * and 16 bit fractional, where 1.0 is max backlight value.<br>
- * bd->props.brightness is 8 bit format and needs to be converted by<br>
- * scaling via copy lower byte to upper byte of 16 bit value.<br>
- */<br>
if (dc_link_set_backlight_level(dm->backlight_link,<br>
- (bd->props.brightness * 0x101), 0, 0))<br>
+ brightness, 0, 0))<br>
return 0;<br>
else<br>
return 1;<br>
-- <br>
2.17.1<br>
<br>
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